The present invention relates to a method of forming a stem and assembling a snap ring in a groove in the stem without expanding the snap ring. Methods of this general type are shown in U.S. Pat. Nos. 1,896,028, 2,464,622, 2,957,237, 3,686,743, 3,702,085 and 4,189,978. Prior methods of forming a groove about which a snap ring is inserted comprised milling the groove in the stem and then deforming the ends of the snap ring to force the snap ring to fit about the daimeter of the stem and then closing the snap ring ends. U.S. Pat. No. 4,916,801 assigned to Shepherd Products U.S., Inc., the assignee of the present invention, also discloses a method of forming a stem with a groove and a snap ring. The method in that patent includes the steps of inserting a nonrotating punch into a recess defined in a pierced extension of the stem and then applying downward force with the punch to peen the pierced extension over the snap ring to form a collar which defines the upper wall of the groove. In utilizing this method, it has been found that in some instances when the punch is forced downwardly to peen over the pierced extension to form the collar, the collar may become ripped or torn. This tearing or ripping of the collar is not only aesthetically displeasing but also leads to progressive cracking or breaking of the extension, causes problems in inserting the stem into furniture bases, and poses risks to assembly personnel of becoming cut with the edges of the torn collar. Stem and snap ring assemblies and other caster retention mechanisms are shown in U.S. Pat. Nos. 3,755,852, 3,834,006 and 4,129,921.